[Sema][ObjC] Process category attributes before checking protocol uses

This ensures that any availability attributes are attached to the
category before the availability for the referenced protocols is checked.

rdar://37829755


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@325994 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaDeclObjC.cpp

@@ -1835,6 +1835,13 @@ ActOnStartCategoryInterface(SourceLocation AtInterfaceLoc,
   // FIXME: PushOnScopeChains?
   CurContext->addDecl(CDecl);
 
+  // Process the attributes before looking at protocols to ensure that the
+  // availability attribute is attached to the category to provide availability
+  // checking for protocol uses.
+  if (AttrList)
+    ProcessDeclAttributeList(TUScope, CDecl, AttrList);
+  AddPragmaAttributes(TUScope, CDecl);
+
   if (NumProtoRefs) {
     diagnoseUseOfProtocols(*this, CDecl, (ObjCProtocolDecl*const*)ProtoRefs,
                            NumProtoRefs, ProtoLocs);
@@ -1846,10 +1853,6 @@ ActOnStartCategoryInterface(SourceLocation AtInterfaceLoc,
                                             NumProtoRefs, Context); 
   }
 
-  if (AttrList)
-    ProcessDeclAttributeList(TUScope, CDecl, AttrList);
-  AddPragmaAttributes(TUScope, CDecl);
-
   CheckObjCDeclScope(CDecl);
   return ActOnObjCContainerStartDefinition(CDecl);
 }

test/SemaObjC/unguarded-availability-category-protocol-use.m

@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -triple arm64-apple-ios10 -Wunguarded-availability -fblocks -fsyntax-only -verify %s
+
+__attribute__((availability(ios,unavailable)))
+@protocol Prot // expected-note {{here}}
+
+@end
+
+@interface A
+@end
+
+__attribute__((availability(ios,unavailable)))
+@interface A (Cat) <Prot> // No error.
+@end
+
+__attribute__((availability(tvos,unavailable)))
+@interface B @end
+@interface B (Cat) <Prot> // expected-error {{'Prot' is unavailable: not available on iOS}}
+@end